The present invention relates to a motor.
An armature of a conventional motor includes a rotation shaft and an armature core and a commutator, which are fixed to the rotation shaft. An armature coil is wound around the armature core. Power is supplied to the armature through a power supply brush that is in slidable contact with the commutator. Japanese Laid-Open Patent Publication No. 2012-178965 describes an example of a motor including an armature coil, which is accommodated in a yoke housing, and a power supply brush, which is held by a brush holder attached to an open end of the yoke housing. Further, a commutator is arranged in a recess of the brush holder. A speed reduction unit that reduces the rotation speed of the rotation shaft and outputs the reduced speed is coupled to the opening of the yoke housing.
In the motor including the power supply brush described above, when the power supply brush is in slidable contact with the outer circumferential surface of the commutator that rotates integrally with the rotation shaft, the power supply brush wears and produces abrasion powder. When the abrasion powder diffuses and deposits in the motor, the abrasion power may form a conductive line between the power supply brush and the rotation shaft and between the power supply brush and the armature core. This may cause an insulation defect.